Surgical instrument

ABSTRACT

An improved surgical tool of the type comprising a handle assembly having a movable tool-operating handle member, a tool head having first and second tissue-engaging members movable between open and closed positions relative to one another, and a mechanism coupling the tool head to the handle assembly for causing opening and closing movement of the tissue-engaging members in response to manipulation of the movable tool-operating handle member. The improved tool is characterized by an inner shaft secured to a stationary part of the handle assembly, and a hollow outer shaft disposed in telescoping relation to the inner shaft, with the tool head being secured to the inner shaft and the outer shaft being movable axially relative to the inner shaft by manipulation of the movable tool-operating handle member, with the outer shaft causing opening and closing of the tissue-engaging members as it undergoes telescoping movement. Preferably an opaque tubular member surrounds the hollow outer shaft so as to conceal movement of the outer shaft. The tool also may include a manually-operated mechanism for selectively rotating the tool head relative to the handle assembly.

INTRODUCTION

This invention relates to surgical instruments and more particularly toinstruments for use in endoscopic surgical procedures, including but notlimited to laparoscopy.

BACKGROUND OF THE INVENTION

Human and animal surgery frequently requires the grasping, manipulatingor cutting of tissue or other organic living matter at some distancefrom the surgeon's hands. In such cases endoscopic surgical methods arecommonly employed that make it possible for skillful and precise surgeryto be conducted despite the fact that the surgical site is a substantialnumber of inches from the point of initial incision in the person oranimal being operated on. Endoscopic surgical procedures encompass botharthroscopic and laparoscopic surgery techniques. In endoscopic surgery,small incisions are made in the exterior surface of the person or animalbeing operated on, and the work being performed is observed by theoperating surgeon by means of a an optical device known as an endoscopewhich is inserted into the person or animal through a small incision.Endoscopic surgical techniques are displacing conventional open surgicaltechniques for many procedures, and hence there is a need for improvedinstruments for conducting such procedures.

A wide variety of surgical instruments have been devised for use inarthroscopic and laparoscopic surgical procedures, including instrumentssuch as graspers, forceps and scissors for use in grasping, cutting orotherwise remotely manipulating bodily tissue and other matter duringsurgery.

A typical instrument employed in endoscopic surgery has a pair ofarticulated jaws, and a handle mechanism comprising two members, onemovable with respect to the other, which can conveniently be manipulatedso as to cause the jaws to open and close. Serrations, blades, cuttingedges, or other features (depending upon the use for which the tool isintended) enable the jaws to perform various surgical functions, such asgrasping or cutting. The articulated jaws are located at the distal endof a relatively long extension of the handle mechanism. The length ofthe extension is determined by the depth of the surgical site, while itscross-sectional dimensions are established by the maximum permissibleincision size.

Many ingenious linkages have been devised for converting the surgeon'smanual efforts at the handle end of the instrument into opening andclosing of the tool's jaws. Most commonly, the surgical tool comprises astationary handle member rigidly joined to a hollow outer shaft and amovable handle member pivotally attached to a coaxial inner shaft in theform of a tube or solid rod that is capable of reciprocal axial movementrelative to the outer shaft, with the jaws being operatively coupledbetween the outer hollow shaft and the inner shaft member so as to openand close in accordance with relative axial movement of the outer andinner shafts. When the surgeon squeezes the stationary and movablehandle members together, the outer and inner shafts coact in such a wayas to make the jaws close. When the surgeon spreads the stationary andmovable handle members apart, the motions are reversed and the jawsopen. Publications illustrating the prior art include U.S. Pat. No.3,404,677 and the prior art cited therein, as well as the followingreferences: U.S. Pat. Nos. 4,836,205; 4,258,716; 4,084,594; 4,393,872;5,026,375; 4,712,545; and 5,026,370.

OBJECTS AND SUMMARY OF INVENTION

A factor involved in the development of this invention is therealization that in the case of surgical scissors involving twotelescoping shafts, having the outer hollow shaft fixed to thestationary handle member, in preference to it being movable and theinner shaft being fixed relative to the stationary handle member, isbeneficial in that it avoids the possibility that apparent movement ofthe outer shaft when the instrument is operated would confuse thesurgeon's depth perception in relation to the surgical site of thepatient, thereby increasing the likelihood of surgical error.

Still other factors involved in development of this invention are theadvantages derived from designing a surgical instrument with discretesubassemblies so as to facilitate (1) manufacture, (2) use ofreplaceable components, and (3) sterilization of selected components orsubassemblies. Another factor considered in making the invention is thedesirability of an instrument design that optionally includes acauterization capability.

Accordingly, the primary object of this invention is to provide animproved surgical tool for use in endoscopic surgical procedures, e.g.,laparoscopic surgery.

Another object of this invention is to provide an improved surgicalinstrument of the type described that is formed of a plurality ofdiscrete subassemblies that facilitate manufacture and final assembly.

Still another object of this invention is to provide a surgical toolhaving a novel handle assembly.

A further object of this invention is to provide a surgical instrumentor tool that comprises a tool head and means for electrifying said toolhead so as to effect cauterization of tissue contacted by said toolhead.

Still a further object is to provide a precision surgical instrument ofthe type described that is characterized by a removable scissors-typecutting head.

Another object of this invention is to provide a surgical instrumentadapted for cutting tissue that does not confuse the surgeon intobelieving that the instrument is moving axially when it is operatedwithout any intention on his part to move it axially.

A further object of this invention is to provide an improved surgicalinstrument of the type that has (1) a handle assembly and (2) a toolhead coupled to and operated by the handle assembly that comprisesco-operating jaws movable into and out of closing relation with oneanother, wherein the jaws are coupled to and operated by a coaxialarrangement of a rod secured to the handle assembly and a hollow shaftslidably surrounding the rod, the improved surgical instrument beingcharacterized means for concealing axial movement of the tube relativeto the handle assembly.

A further specific object of this invention is to provide a surgicalinstrument characterized by a movable tube and a sheath that concealsaxial movement of that tube.

Another specific object of the invention is to provide a surgical toolfor use in various surgical procedures, including but not limited toendoscopic procedures for arthroscopy and laparoscopy, that comprises ahandle and trigger assembly separably connected to an operating toolassembly that in turn comprises a hollow shaft and a rod telescopicallymounted to one another, means for securing the rod to the handleassembly, and means connecting the hollow shaft to the trigger assemblywhereby operation of the trigger will cause the shaft to move axiallyrelative to the rod.

Another specific object of this invention is to provide a novel surgicalinstrument that is adapted for monopolar electrification, so as topermit cauterization at the surgical site.

The foregoing objects are obtained by providing a surgical instrument ortool that comprises a handle assembly having first and second handlemembers movably connected for movement relative to one another, anelongate rod releasably secured to the first handle member so as to forma fixed extension thereof, a tool head coupled to the rod having firstand second members movable toward and away from one another, a tube(hollow shaft) coaxially and slidably surrounding the rod, with the tubehaving a first end slidably received in the handle assembly and a secondend in position to be moved into and out of overlapping relation withsaid first and second members of said tool head, and drive meansconnecting said hollow tube and one of said handle members for causingsaid tube to shift axially relative to said rod between (1) a firstretracted position when said one handle member is moved to a firstposition relative to the other handle member and (2) a second extendedposition when said one handle member is moved to a second positionrelative to said other handle member, said first and second members ofsaid tool head being in a first open position relative to one anotherwhen said one handle member is in its said second position and beingforced by said tube to close relative to one another when said onehandle member is moved to its said first position. In a preferredembodiment of the invention, (1) the tool head is detachable from theaforementioned rod and replaceable by another like or different toolhead; (2) the tool head is rotatable relative to the handle assembly;(3) the rod, tool head and hollow tube form a subassembly that isreadily detachable from the handle assembly; and (4) the tool head maybe electrified for monopolar cauterization.

Other necessary and optional features are disclosed by or renderedobvious by the following detailed description which is to be consideredtogether with the accompanying drawings.

THE DRAWINGS

FIG. 1 is a side elevation of a preferred embodiment of the inventionconstituting a surgical scissors designed for laparoscopic surgery;

FIG. 2 is a side view in elevation of the left hand half of the handlehousing;

FIG. 3 is a side view in elevation of the right hand half of the handlehousing;

FIG. 4 is a front view in elevation of the handle part shown in FIG. 3;

FIG. 5 is a side elevation of the insulator housing;

FIG. 6 is a sectional view in side elevation of the insulator housingtaken along its center line;

FIG. 7 is a rear end view of the insulator housing;

FIG. 8 is a front end view in elevation of a cap for the insulatorhousing;

FIG. 9 is a side view in elevation of the end cap of FIG. 8;

FIG. 10 is a fragmentary longitudinal sectional view in side elevationshowing the handle assembly without the right hand half of the handlehousing;

FIG. 11 is a plan view of a rod to which the tool head is connected;

FIG. 12 is a side view showing the rod of FIG. 11 rotated 90° on itsaxis;

FIG. 13 is a side view of a helical gear that is affixed to the rod ofFIG. 11;

FIG. 14 is an end view of the gear of FIG. 13;

FIG. 15 is a cross-sectional view taken along line 15--15 of FIG. 1;

FIG. 16 is a cross-sectional view along line 16--16 of FIG. 1;

FIG. 17 is a cross-sectional view taken along line 17--17 of FIG. 1;

FIG. 18 is a side view in elevation of the tube housing;

FIG. 19 is a longitudinal sectional view in elevation of the tubehousing;

FIG. 20 is a bottom plan view of the tube housing;

FIG. 21 is a front end view of the tube housing;

FIG. 22 is an enlarged cross-sectional view of a portion of the toolhead drive assembly;

FIG. 23 is a cross-sectional view taken along line 23--23 of FIG. 22;

FIG. 24 is a cross-sectional view taken along line 24--24 of FIG. 22;

FIG. 25 is a side elevation of the operating trigger member;

FIG. 26 is a front end view in elevation of the trigger member of FIG.25;

FIG. 27 is a side view in elevation of the rotational trigger member;

FIG. 28 is an exploded view showing how the tool head is detachable fromits supporting rod;

FIG. 29 is a top plan view of one of the scissors blade members;

FIG. 30 is a top plan view of the tool (scissors) head in open position;and

FIG. 31 is a fragmentary sectional view showing inclusion of a springfor holding the trigger member in its forward position.

It is to be understood that some of the several views presented by thedrawings are drawn to different scales for ease of illustration anddescription. Also, like parts and features are identified by likenumerals in the drawings.

PREFERRED EMBODIMENT OF INVENTION

Referring now to FIG. 1, there is shown a surgical instrument which, inits preferred form, is a scissors designed for laparoscopic procedures.The instrument comprises a handle assembly 2, a drive assembly 4, a toolhead 6 in the form of a scissors head, and an electrical terminal pin 7.The handle assembly may take various forms. In this preferred embodimentof the invention, the handle assembly comprises a fixed or stationaryhandle 8, a movable handle member in the form of a trigger 10 foroperating the scissors head, and a rotation trigger member 12 whichcooperates with the drive means carried by the handle assembly to effectcontrolled rotation of the scissors head relative to the handleassembly.

Looking now at FIGS. 2-4, the fixed handle 8 comprises complementaryleft-hand and right-hand handpieces 16L and 16R that preferably are madeof a plastic material such as a polysulfone or polycarbonate. Thesehandpieces are complementary in the sense that they are mating halves ofmember 8 and, except as otherwise stated hereinafter, handpieces 16L and16R are identical mirror images of one another. Handpieces 16L and 16Rhave like circularly curved axially-extending elongate cavities 20L and20R respectively on their mutually confronting sides. Additionally,handpieces 16L and 16R have axially-extending flat-sided grooves 22L and22R that intersect cavities 20L and 20R respectively at the twelveo'clock position (FIG. 4). Grooves 22L and 22R cooperate to define akeyway for an insulator housing 42 (FIGS. 5-7) described hereinafterthat forms part of the drive assembly 4. Handpieces 16L and 16R alsohave semi-circular cavities 24L and 24R that communicate withreduced-diameter semi-circular cavities 26L and 26R respectively.Intersecting the cavities 24L and 24R are additional semi-circularcavities 28L and 28R which also intersect the cavities 20L and 20Rrespectively at right angles. Cavities 20L, 20R, 24L, 24R, 26L, 26R, 28Land 28R are semi-circular in the sense that they have a semi-cylindricalcross-section. The left handpiece 16L is provided with three projectionsor pins 32A, 34A and 36A of circular cross-section that are sized tomake a close fit in like-spaced cavities or depressions 32B, 34B and 36Bin the right handpiece 16R. Although provided for other purposeshereinafter described, pins 32A, 34A and 36A serve incidentally asassembly registration pins for handpieces 16L and 16R.

Preferably, but not necessarily, one handpiece (16L) has two or morelocating pins 37A that are sized and located so as to mate closely withshallow depressions or cavities 37B in the other handpiece (16R), so asto facilitate and assure proper registration of the two handpieces whenthey are engaged with one another in forming handle 8. Handpieces 16Land 16R are secured together, preferably by a suitable cement such as anepoxy resin or by ultrasonic welding.

For reasons of convenience of use by the surgeon, it is preferred, butnot essential, that the rear surface of the left and right handpieceshave a knurled configuration as shown at 38L and 38R respectively so asto facilitate gripping of the handle unit. Additionally, it ispreferred, but not essential, that the handpieces be provided withcomplementary finger holes 40L and 40R for receiving the thumb of thesurgeon.

Drive assembly 4 comprises an insulator housing 42 and a tube housing106 (see FIG. 10 and FIGS. 5-7 and 18-21), plus components (other thantool head 6) that are attached to housings 42 and 106.

Cavities 20L and 20R in the two handpieces cooperate to form acylindrical chamber for receiving insulator housing 42. The latter,which preferably is made of the same material as handpieces 16,comprises a cylindrically shaped elongate section 44 having a peripheralflange 46 at its forward or distal end so as to provide a shoulder 48that engages the forward end surfaces 50L and 50R of the left and righthandpieces. Tubular section 44 is formed with an externallongitudinally-extending rectangular rib 52 at the twelve o'clockposition (as viewed in FIG. 7) that is sized to make a close sliding fitin the keyway formed by grooves 22L and 22R of the left and righthandpieces 16L and 16R respectively. In addition, tubular section 44 hasan axially-extending slot 56 (FIG. 7) formed symmetrically about the sixo'clock position (as viewed in FIG. 7) that serves as an access hole forportions of trigger members 10 and 12 and a slide hole for a portion oftube housing 106. As viewed in FIG. 7, slot 56 terminates in side edgesurfaces 84A and 84B. The circumference of section 44 in the portionhaving slot 56, i.e., the circumference measured between the outer edgesof side edge surfaces 84A and 84B, measures about 260°, so that slot 56extends through an angle of about 100° (50° on either side of the sixo'clock position). As viewed in FIGS. 5-7, slot 56 starts at theproximal (rear) end of section 44 and ends close to the midpoint ofhousing 42, leaving an arcuate end surface or shoulder 57 (FIG. 6).

Insulator housing 42 has a center bore 60 which is of constant diameterthroughout its length, except that (1) at its distal (front) end it istapered as shown at 62 and then communicates in turn with a smallerdiameter hole 64 and a bore 66 that has a slightly larger diameter thanhole 64 so as to form an annular shoulder 65, and (2) it is formed withan internal rectangular axially-extending rib 78 at the six o'clockposition (as seen in FIG. 7). Preferably the proximal (rear) end of rib78 is bevelled as shown at 79. Affixed to the proximal (rear) end of theinsulator housing 42 is an end cap 80 (FIGS. 8 and 9) that preferably ismade of the same material as handpieces 16. End cap 80 is generallycircular in cross-section except that its circumference is less than afull 360°, so as to provide flat bottom surfaces 82A and 82B. Preferablyits circumference, measured between the outer edges of surfaces 82A and82B (as viewed in FIG. 8) measures about 240°. Consequently when cap 80is applied to housing 42 so that its surfaces 82A and 82B extendparallel to bottom edge surfaces 84A and 84B, a portion of the rear endsurface 58 of housing 42 in the region of the six o'clock position isnot covered by cap 80, so as to allow clearance between the cap andtrigger 10 when it is desired to pull the drive assembly out of thehandle assembly.

Cap 80 is provided with a radially-extending through slot 88 thatterminates at the center of the cap with a circularly curved hole 90that is concentric with the center axis of the cap. Also cap 80comprises a reduced diameter body section 92 and a peripheral flange 94.Body section 92 is sized to make a close fit in the proximal end of theinsulator housing, with flange 94 having the same o.d. as tubularsection 44. The cap is ultrasonically welded or cemented, e.g., by anepoxy resin, to the proximal end surface 58 of housing 42, with thecircularly curved hole 90 being concentric with the hole 64 of housing42.

As shown in FIG. 10, insulator housing 42 is disposed in the cylindricalchamber formed by the mating cavities 20L and 20R of handpieces 16, withshoulder 48 engaging the forward end surfaces 50L and 50R of thosehandpieces and rib 52 being disposed in the keyway formed by grooves 22Land 22R. The interlocking of rib 52 with the keyway formed by grooves22L and 22R serves to dictate orientation of housing 42 relative to thehandle assembly. Housing 42 is releasably secured in handle assembly 2by a locking action between a terminal pin 7 and rod 100 as hereinafterdescribed.

Referring now to FIGS. 10-14 and 18-27, drive assembly 4 comprises, inaddition to insulator housing 42, the following elements: a support rod100 for tool head 6, an outer operating tube or sleeve 102, an outersheath in the form of a tube 104, and a tube housing 106. The outersheath 104 is cylindrical and its proximal (rear) end extends into axialbore 66 in engagement with shoulder 65 and is fixed to the insulatorhousing by a press fit or in some other suitable way, e.g., by an epoxycement, as permitted by the materials being secured together. In thispreferred embodiment, sheath 104 is made of a suitable electricallyinsulating material, e.g., a fluorinated hydrocarbon such as Teflon,while tube 102 may be made of an electrically-conductive metal or aconductive plastic. Tube 102 has an outer diameter sized so that itmakes a close sliding fit within outer sheath 104 and also in thereduced diameter hole 64.

Referring now to FIGS. 18-21, tube housing 106 preferably is made of alubricious plastic material, e.g., molded DELRIN. Housing 106 is ahollow member formed with a rectangular aperture 110 that is centeredabout the six o'clock position and extends through about 100° of itscircumference. Aperture 110 is located just short of the proximal orrear end of the tube housing, so as to form a depending lug section 112which serves as part of the pivotal connection for the trigger member10. Housing 106 also is provided with an axially-extending slot 114 thatintersects aperture 110 and splits the lug section 112 into two likeparts 112A and 112B (FIG. 20). Additionally, housing 106 has an externalaxially-extending shallow groove 116 located at approximately the sixo'clock position. Groove 116 is aligned with and has substantially thesame width as slot 114. Groove 116 slidably mates with the elongate rib78 on the inner surface of insulator housing 42. The slidinginterengagement of groove 116 with rib 78 prevents the tube housing fromrotating relative to insulator housing 42 and also aligns aperture 110with slot 56.

Referring now to FIG. 19, the axial bore of tube housing 106 ischaracterized by a first relatively large diameter section 122, atapered section 124, a relatively small intermediate section 126 and anintermediate diameter size section 128. Axial bore section 126 is sizedto make a close sliding fit with support 100. The intermediate size boresection 128 is sized so as to tightly accommodate the proximal (rear)end of tube 102. The latter is fixed to tube housing 106 by a press fitor by other suitable means, e.g., by a cement or by soldering, brazingor welding as is deemed practical according to the materials beingjoined.

Referring now to FIGS. 11 and 12, for the majority of its length, rod100 has a constant relatively large size diameter as shown at 134. Theproximal end of rod 100 is provided with a rounded head section 136which is sized to make a close fit in the rounded rear end of thechamber formed by the mating cavities 28L and 28R. Intermediate sections134 and 136 the rod has two reduced diameter sections 138 and 140 thatare separated by an intermediate flange section 142 which preferably hasa diameter close to that of rod section 134. An annular shoulder 141 isformed by the rod at its section 138. The opposite or distal end of rod100 is formed so as to accommodate the tool head 6. Further details ofthe construction of the forward or distal end of support rod 100 arepresented hereinafter.

The proximal (rear) end of rod 100 slidably extends through the boresection 126 of tube housing 106 and its intermediate or reduced diametersection 138 is accommodated by and makes a close fit in the circularlycurved center hole 90 of cap 80. The radius of the hole 90 of cap 80 issmaller than the radius of the flange section 142 of the drive rod,while the length of rod section 138 is only slightly greater than theoverall thickness of cap 80. As a result, shoulder 141 and flange 142engage opposite sides of cap 80, thereby preventing rod 100 from movingaxially relative to cap 80, and vice versa. Hence, if rod 100 isinserted into tube housing 106 and tube 102, and that resultingsubassembly is then inserted into the insulator housing via its openend, and thereafter the reduced diameter plug section 92 of cap 80 issecured in the circularly curved section 44 of the insulator housing 42,rod 100 will be fixed relative to the insulator housing while tubehousing 106 and tube 102 will be free to move axially relative to therod and the insulator housing to the extent permitted by the differencein the length of tube housing 106 and the distance between end cap 80and the junction of bore sections 60 and 62.

Looking now at FIGS. 10-14 and 17, rod 100 has a knurled section 146which is slightly larger in diameter than its section 134 and is sizedto accommodate a helical gear 148 having a center hole 149. The lattermay be affixed to rod 100 by a press fit with knurled surface 146, or bymeans of a suitable cement or other fixing agent, e.g., an epoxy cement.Gear 148 may be made of a metal or a plastic. Rod 100 is preferably madeof metal for electrical conduction purposes. The preferred mode ofmounting helical gear 148 to the drive rod is by way of a friction fit,augmented by a suitable cement. Gear 148 has evenly shaped,helically-directed gear teeth 150. Gear 148 is sized so that a portionof its periphery projects through aperture 110 in tube housing 106 forengagement of its teeth 150 by the rotation trigger member 12 (FIGS. 10,17 and 27).

Trigger member 12 has an elongate hole 154 for accommodating pivot pin36A. Additionally, one end of that rotation trigger is provided with aplurality of helically pitched teeth 156 which are shaped and sized tomate with teeth 150 of gear 148. The opposite end of the trigger memberis preferably knurled or formed with grooves 160 to eliminate slippagebetween the rotation trigger member and the surgeon's finger used tooperate that trigger member. Trigger member 12 also has an extension 162provided with a small aperture 164 which is sized to accommodate one endof a tension spring 166. The opposite end of the spring is formed with acircular extension sized to fit over pin 34A of the left handpiece 16L.Pivot hole 154 is elongated so as to facilitate operation of therotation trigger. When the latter is mounted to pin 36A, spring 166exerts a force that normally holds the rotation trigger in its forwardand down position (FIG. 10), with its teeth 156 being out of engagementwith gear 148. When that trigger is pulled back by a finger of theoperating surgeon, its moves upwardly on pivot pin 36A and also rotateson that pin, causing its teeth 156 to engage and rotate helical gear144, thereby causing rotation of drive rod 100. Rotation of trigger 12is limited in one direction by its engagement with the surface 57defining the forward end of slot 56 of the insulator housing 42, and inthe other direction by its engagement with shoulders 170L and 170R(FIGS. 2 and 3) formed by handpieces 16L and 16R.

Referring now to FIGS. 10, 16, 25 and 26, trigger member 10 ispreferably formed with an elongate aperture 180 to accommodate a fingerof the surgeon. Additionally, the trigger member has a hole 182 toaccommodate pivot pin 32A on the left handpiece. The trigger member hasa reduced thickness end portion 190 that is provided with a rectangularnotch 192 that subdivides its upper end into two fingers 193 and 195.The notch and fingers are sized so as to make a pivotal connection withlug 112 of tube housing 106. It is to be noted that handpieces 16L and16R have recesses 17L and 17R to accommodate the reduced thickness endportion 190 of the trigger member. Trigger member 10 is pivotallymounted so that its notch 192 is engaged with lug 112. Pivotal movementof trigger 10 causes axial movement of tube housing 106 and tube 104when the trigger member is pivoted toward and away stationary handle 8.Pivotal movement of trigger 10 relative to the stationary handle 8 isillustrated by the arrows in FIG. 1. Pivotal movement of trigger 10causes the tube housing to move in insulator housing 42 between a firstrearward limit position (FIG. 1) wherein tube housing 106 is stopped byengagement with end cap 80 and a second forward limit position whereinthe distal (forward) end of the tube housing is blocked by the taperedbore section 62 of the insulator housing.

Referring now to FIGS. 10 and 15, the electrical terminal pin 7 is madeof metal and comprises a round pin section 210 and an enlarged headsection 212. Preferably pin section 210 is bifurcated as a result of aslot 214 so as to be compressible radially when coupled to a matingfemale connector. Head section 212 is generally round in cross-sectionexcept that it has diametrically opposed flat surfaces that mate withcorresponding flat surface portions 25A and 25B (FIG. 2) of cavities 24Land 24R. Pin 7 also has a keyhole that extends perpendicular to its flatsurfaces and comprises an enlarged section 216 and a reduced section218. The latter section has a radius of curvature larger than that ofsection 140 but smaller than that of flange 142 and rounded end 136 ofrod 100. The enlarged section 216 has a radius of curvature larger thanthe rounded end 136 of rod 100. A compression spring 222 surrounds pinsection 210 in the hole formed by cavities 24L and 24R, being captivatedbetween head section 212 and the shoulder formed by the intersection ofcavities 26L and 26R with cavities 24L and 24R respectively. Spring 222normally urges the terminal pin inwardly so as to have rod section 140locked in keyhole section 218.

Referring now to FIGS. 13-15 and 22, tool head 6 can take various forms.In this preferred embodiment of the invention, it takes the form of areleasable scissors-type head.

In this connection it should be noted that it is preferred to providethe outer tube or sleeve 102 with a tubular sleeve-type bearing 230(FIGS. 22 and 24) having a peripheral flange 232. Bearing 230 fitsinside of and is bonded to tube 102, with the distal end of the tubeengaging peripheral flange 232 as shown in FIG. 22. Bearing 230 may bemade of TEFLON or some other commercially available material that has arelatively low coefficient of friction and the hardness required towithstand wear from repeated sliding contact with the tool head. Thei.d. of bearing 230 is slightly larger than the o.d. of rod 100 and theo.d. of the body sections 250 of scissors blade members 246A and 246Bhereinafter described.

Referring now to FIGS. 1, 22-24 and 28-30, tool head 6 is detachablysecured to rod 100 so as to be locked against rotational or axialmovement relative to the rod. For this purpose, rod 100 is provided witha tongue 240 having an enlarged head 242, with both the tongue and headhaving a pair of flat opposite surfaces 241 and 243 respectively. Toolhead 6 is preferably formed of two identical scissors blade members 246Aand 246B formed of a stainless steel with spring-like quality. Eachblade member comprises a body section 250 that is semi-circular incross-section, so as to have a flat face 252. In addition, each bodysection is notched and its flat face 252 is recessed as shown at 260 and262 so that when the two faces are brought into confronting relationwith one another, a bayonet slot 264 is formed as shown in FIG. 28 thatis sized to mate with tongue 240 of rod 100 as shown in FIG. 22.

Still referring to FIGS. 22-25, blade members 246A and 246B are formedwith spring arms 268 that are integral with body sections 250 and carryintegral scissors blades 270. Arms 268 are formed so that in theirnormal state the scissors blades extend at an inclined angle to thelongitudinal axes of body sections 250 (FIG. 28). An edge portion ofeach scissors blade is ground so as to provide a micropolished flatscissors face as shown at 272 that terminates in a sharp edge 274. Eachscissors blade 270 is formed so that it is bent longitudinally as viewedin FIG. 30, so that its forward end or tip crosses the center axis ofits associated body section 250. Accordingly, when the two scissorsblade members are secured together at their flat faces 252 (FIG. 28) bywelding or other means, so as to form bayonet slot 264, the scissorsfaces 272 are engaged with one another at their proximal or rear ends(FIG. 30), while their forward ends are separated (spaced apart) fromone another (FIG. 28) but extend laterally across the center axis of thetool head, i.e., across the planes of faces 252. Consequently, if aradially-directed squeezing force is applied to blades 270 normal tofaces 252 (as represented by the mutually-converging arrows in FIG. 28),the blades will be forced together, and when that occurs, the resultinginterference caused by the fact that the blades cross one another (asseen in FIG. 30) will cause the blades to deflect back away from oneanother to an extent just sufficient to permit the sharp edges 274 toclose on one another in a scissors-like cutting action.

As seen in FIG. 22, the scissors head 6 is sized so that its bodysections 250 can slide within bearing sleeve 230. Also, blades 270 aresized so that they also can fit within and slide relative to bearing 230when they are fully closed on one another.

Assembly of the tool involves several separately conducted subassemblyprocedures. The tool head 6 is assembled by welding or brazing blademembers 246A and 246B together. In a separate procedure, helical gear148 is mounted onto and secured to rod 100. Then tool head 6 is attachedto rod 100 by inserting the rod's tongue 240 into bayonet slot 264.

Contemporaneously, or before or after the foregoing steps, tube 102 isaffixed to tube housing 106, and tubular sheath 104 is affixed toinsulator housing 42. Thereafter, rod 100, with tool head 6 attached, isinserted into the proximal (rear) end of tube housing 106 and forcedforwardly so as to cause the scissors blade arms 268 to yield enough toallow scissors blades 270 to close on one another enough to permit thetool head to pass through tube 102 and bearing 230, and also to locategear 148 in bore section 122. The diameter of bore section 122 isslightly oversized with respect to helical gear 148 so as to permit thegear to rotate therein. Thereafter, or before insertion of rod 100 intothe tube housing, end cap 80 is mounted onto rod 100 as previouslydescribed. In this connection, it is to be noted that the semi-circularhole 90 in cap 80 is slightly larger than the diameter of rod section138, while preferably the width of slot 88 in cap 80 is slightly smallerthan the diameter of rod section 138, with the result that the end capmakes a snap fit with the drive rod. Molded cap 80 has flexibility thatpermits it to yield enough to allow rod 100 to be forced through slot 88into hole 90.

Thereafter, the subassembly consisting of tube 102, tube housing 106,rod 100 with gear 148, and tool head 6, is slipped into the proximal(rear) end of insulator housing 42, with the internal rib 78 of theinsulator housing being aligned and disposed in groove 116 and slot 114of the tube housing. This step involves inserting tube 102 into sheath104 so that blades 270 can project from the forward (distal) end of thesheath. When the subassembly consisting of tube 102, tube housing 106,etc., is inserted into the insulator housing, it is preferred that rod100 be withdrawn enough in tube housing 106 (as viewed in FIGS. 10 and22) to permit sleeve bearing 230 to surround scissors blades 270 andthereby apply a radially directed compression force that holds theblades in closed position. Having the scissors blades closed by bearing230 facilitates insertion of the blades and tube into sheath 104.Thereafter rod 100 is shifted axially so as to permit end cap 80 to beseated in the rear end of the insulator housing, and end cap 80 issecured to that housing by a suitable cement or by ultrasonic welding aspreviously described. The internal rib 78 in insulator housing 42cooperates with groove 116 and slot 114 to insure that the aperture 110of the tube housing is in confronting alignment with the trigger member10 when subsequently the resulting assembly is mounted to the handleassembly.

The foregoing combined subassemblies consisting of insulator housing 42and its attached sheath 104, and tube housing 106 and its associatedparts, is then combined with the handle assembly. The latter may bepreassembled by starting with left handpiece 16L and first mountingtrigger member 10 on pivot pin 32A. Simultaneously, or before or afterthe foregoing step, the rotational trigger 12 is placed onto the post36A with its teeth engaged with helical gear 148, and the spring 166attached thereto is subsequently attached to the post 34A. Then terminalpin 7, with compression spring 222 mounted thereon, is placed intocavities 24L and 26L, with spring 222 being compressed so as to providea force urging pin 7 inwardly (downwardly as viewed in FIG. 10). Thenthe right handpiece 16R is placed over the foregoing assembly intoengagement with the left handpiece 16L and the two handpieces aresecured together by a suitable cement or by ultrasonic welding.

The handle assembly is attached to the assembly consisting of insulatorhousing 42 and tube housing 106, etc. by the simple expendent ofinserting the insulating housing into the front end of the chamberformed by cavities 20L and 20R. When this is done, the rounded rear endof rod 100 engages the small keyhole section 218 and coacts with theedge of that keyhole section to cam pin 7 outwardly enough to align theenlarged keyhole section 216 with the rod, thereby allowing rod section140 to be forced into alignment with the pin, whereupon spring 222 willforce the pin inwardly again to lock rod 100 to the terminal pin, inturn locking the insulator housing to the handle assembly.

It is to be noted that when inserting the insulator housing into thehandle assembly, the trigger 10 must be pulled back to its rear limitposition as shown in FIG. 10 so as to permit the insulator housing 42and cap 80 to clear the finger section 193 of the trigger, but thefinger section 195 projects up far enough to intercept the lug.Thereafter, assuming that the insulator housing has been locked to thehandle assembly, reverse movement of the trigger back to the position ofFIG. 1 will cause finger section 193 to engage the lug and thereby movethe tube housing rearwardly in the insulator housing.

As mentioned hereinabove, the elongate pivot hole 154 of the rotationaltrigger is sized so that spring 166 will hold it in a down and forwardposition (FIG. 10), in which position its teeth 156 do not protrude intothe insulator housing far enough to intercept gear 148 and thusinterfere with its axial movement when the tool assembly comprising theinsulator housing and tube housing 106 is inserted into or pulled out ofthe handle assembly. To further facilitate detachment of the toolassembly from the handle assembly, the slot 114 in tube housing 106 issized so as to provide clearance with trigger teeth 156 as the housingis inserted into or removed from the handle housing 16L,16R.

Operation of the tool is as described hereinafter.

When trigger member 10 is in its forward limit position (FIG. 1), tubehousing 106 and tube 102 are in their withdrawn or retracted positionwherein bearing 230 terminates short of engagement with the blades 270of tool head 6, with the result that the blades are in their separatedor open position (FIGS. 1, 22 and 28). When trigger member 10 is pulledtoward fixed handle 8 to its other limit position (FIG. 10), the pivotalconnection between the trigger member and lug 112 of tube housing 106causes the latter to be moved forward in housing 42, causing tube 102 totelescope forwardly and causing bearing member 230 to slip over andcompress scissors blades 270 into closing position.

The angular orientation of scissors blades 230 relative to the handleassembly can be varied by manipulation of rotational trigger member 12.When trigger member 12 is pulled back, its gear teeth cause helical gear148 to rotate, thereby rotating rod 100 and the tool headcounterclockwise (as viewed in FIG. 17) relative to the fixed handlemember 8. Because trigger member 12 has only a limited number of teeth,it must be retracted and then released several times in order to rotatethe tool head 360°. By way of example but not limitation, the number ofteeth on rotational trigger 12 and the number of teeth and the pitchthereof on helical gear 148 may be set so that trigger 12 must be pulledback and released approximately 8 times in order to achieve a 360°rotation of the tool head.

The preferred tool design described above offers a number of advantages.For one thing, the tool comprises several discrete lower tiersubassemblies plus two discrete higher tier or major subassemblies, oneof the major subassemblies being a multi-component handle assembly andthe other comprising insulator housing 42, sheath 104, cap 80, tubehousing 106, tube 102, rod 100, helical gear 148 and tool head 6, withthe latter major subassembly being releasably secured to the handleassembly. Detachment of this higher tier or major subassembly from thehandle assembly is achieved by pulling the terminal pin outwardly(upwardly as viewed in FIG. 10) so as to align the enlarged portion 216of its keyhole with the rounded head 136 of rod 100, thereby allowingthe handle assembly to be pulled free of rod 100. As a result, the majorsubassembly comprising insulator housing 42, sheath 104, cap 80, tubehousing 106, tube 102, rod 100, helical gear 148 and tool head 6 can bereplaced by a new and like substitute subassembly. In other words, thehandle assembly is reusable with different substitute tool assemblies.

A second advantage resides in the fact that the scissors head shown inthe drawings is removable from rod 100. A third advantage is thatdifferent tool heads may be used in place of the scissors head shown inthe drawings. Thus, for example, the tool head may be a grasper headcomprising a pair of jaws with confronting serrated surfaces that can beforced together by forward movement of tube 102 into grasping relationwith tissue at a surgical site. The tool head also may comprise acombination grasper/cutter with one of the confronting faces of the twojaws having a cutting blade that is received in a notch in the otherjaw. Another possibility is a tool head with cooperating members forholding a suture or a needle.

A fourth advantage resides in the fact that cap 80 need not be cementedto the insulator housing. Instead, as shown in dotted lines in FIG. 9,the cap could be provided with a peripheral groove 93 in its reducedsection 92 and the insulator housing may be formed with an internalcircumferentially-extending rib (not shown) sized to make a snap fit ingroove 93, thereby permitting the cap to be releasably interlocked withthe insulator housing. If such arrangement is adopted, the cap may beeasily detached from the insulator housing out of connection with rod100, thereby permitting the rod and its attached tool head to bewithdrawn rearwardly out of tube 102 and insulator housing 42. Thisalternative embodiment facilitates removal and replacement of thesubassembly consisting of rod 100, helical gear 148 and the tool head 6,or simply of replacement of the tool head 6.

A further advantage resides in the fact that the rotational triggerpermits the surgeon to rotate the scissors blades relative to the handleassembly by a precise amount, thereby avoiding the need to rotate thehandle assembly to achieve a particular cutting orientation of thescissors blades. The latter advantage is beneficial to the surgeon fromthe standpoint of comfort and ease of manipulation and ease ofoperation.

Still another advantage resides in the fact that bearing sleeve 230applies a like force to each of the two scissors arms 268, with theforce being distributed evenly about the circumference of the curvedouter surfaces of scissors arms 268. Bearing 230 coacts with scissorsarms 268 to urge blades toward one another as they are forced to closeon one another.

A particularly significant advantage of this invention resides in thefact that rod 100 is stationary and surrounding tube 102 is reciprocatedby manipulation of trigger member 10. This invention recognizes thatsurgeons need a point of reference in order to determine if and whenthey are moving a surgical scissors relative to the surgical site. Inthe absence of sheath 104, movement of outer tube 102 as seen by thesurgeon might have a tendency to confuse the surgeon into believing thatthe tool is moving axially relative to the patient. The provision ofouter sheath 104 eliminates the possibility of such confusion. Sincesheath 104 is at least coextensive with tube 102 (and preferablyprojects slightly forward of tube 102 even when the tube is moved to itsforwardmost position relative to rod 100) and hence conceals any axialmovement of that tube relative to handle assembly 2, manipulation ofhandle members 8 and 10 causing the jaws to open and close isaccomplished without the surgeon realizing that there is actual axialmovement of tube 102. Instead, the surgeon sees that sheath 104 isstationary, with the result that the surgeon is free to concentrate hisattention on the actual position of the scissors blades 230 (the latterdo not appear to move toward and away from the patient when the jaws areopened or closed, unless the surgeon actually moves the tool relative tothe patient).

Still another significant advantage is that the tool described above isadapted to conduct monopolar cauterization, but also may be used withoutbeing electrified. If the tool is to be made for non-cauterization uses,pin 7 need not be an electrically-conductive element and instead mayfunction simply as a locking device for rod 100 as hereinabovedescribed.

Other advantages will be obvious to persons skilled in the art.

MODIFICATIONS OF THE INVENTION

Persons skilled in the art will also appreciate that the invention issusceptible to various modifications. Thus, as noted above, variousforms of tool heads may be used in practicing the invention. Also thetool head 6 may be permanently secured to the rod 100. Additionally, themanner of connecting various components may be varied. Thus, theproximal (rear) end of tube 102 may be externally threaded to mate withan internal thread formed in the bore section 128 of tube housing 106.Also, the insulator sheath 104 may be formed of a material which issufficiently rigid to permit it to be formed with an external screwthread, thereby permitting it to mate with a cooperating internal threadformed in bore 66 of insulator housing 42. A further possiblemodification resides in the fact that a different tool head may beattached to the operating rod 100. For example, the tool head maycomprise a grasper arrangement, e.g., a grasper arrangement as disclosedin U.S. Pat. No. 3,404,677, issued Oct. 8, 1968 to H. A. Springer for"Biopsy And Tissue Removing Device".

FIG. 31 shows another modification of the invention wherein acompression spring 290 is mounted on rod 100 between the forward end oftube housing 106 and the tapered bore section 162 of insulator housing42. Spring 290 urges tube housing 106 rearwardly in the insulatorhousing so that it is intercepted by cap 80, in which position the tubehousing holds trigger member 10 in its forward (open) position as shownin FIG. 1.

Still another possible modification is to provide a different form ofpivotal connection between trigger 10 and tube housing 106. Thus, forexample, tube housing 106 could be provided with a radially-extendingexternal projection having a pivot hole, and trigger member 10 could beprovided with a pivot hole designed to mate with the pivot hole on theexternal extension of the tube housing, with a separate pivot pin beinginserted into the mating pivot holes and secured in place so as topivotally connect the trigger to the extension on the tube housing.

Still another possible modification involves connection of theelectrical terminal pin to drive rod 100. It is envisioned that theproximal (rear) end of rod 100 may be provided with a threadedaxially-extending hole, and the terminal pin may be attached to rod 100by providing the terminal pin with an externally-threaded front end thatscrews into the tapped hole in the end of the rod. In such event, theterminal pin may extend parallel rather than at a right angle to thelongitudinal axis of the insulator housing. A further possibility is touse a separate electrically conductive screw to secure the conductiveterminal pin to the threaded axially extending hole in the rear end ofrod 100.

Another contemplated modification is to provide a scissors head whereinthe two blade members 246A and 246B are not permanently secured togetherby welding or brazing but instead are releasably or permanently affixedin an adapter member (not shown) that is designed to mate with theforward end of rod 100. The adapter may be releasably or permanentlycocupled to the rod.

Since still other changes may be made in the apparatus without departingfrom the scope of the invention herein involved, it is intended that allmatter contained in the above description or shown in the drawings shallbe interpreted in an illustrative and not in a limiting sense.

What is claimed is:
 1. A surgical instrument comprising:a handleassembly, said handle assembly having a handle unit and a trigger memberpivotally mounted to said handle unit, said trigger member being movableon its pivot between first and second positions; an elongate rod havinga proximal end and a distal end; means mounted in said handle unit forreleasably securing said proximal end of said rod to said handle unit sothat said rod forms an extension thereof; a tool head attached to saiddistal end of saidrod, said tool head comprising first and secondcooperating tool members movable relative to one another between a firstopen position and a second closed position, said first and second toolmembers normally being in said first open position; a hollow tubecoaxially and slidably surrounding said rod, said tube having a firstproximal end slidably received in said handle unit and a second distalend that is movable into and out of overlapping relation with said firstand second operating tool members as said hollow tube is reciprocatedaxially relative to said rod; force transmitting means connecting saidhollow tube and said trigger member for causing said hollow tube toshift axially relative to said rod between (1) a first retractedposition when said trigger member is in its said first position and (2)a second extended position when said trigger member is in its saidsecond position, said first and second tool members being in said firstopen position and said distal end of said hollow tube being in anon-biasing position relative to said tool head when said hollow tube isin its first retracted position, said distal end of said hollow tubeoverlapping and biasing said said first and second tool members intosaid second closed position when said hollow tube is moved to its saidsecond extended position, said force transmitting means comprising acoupling member attached to the proximal end of said hollow tube andsurrounding said rod; and means attached to said handle unit forslidably supporting said coupling member for reciprocal movementrelative to said rod lengthwise of the axis of said rod; said forcetransmitting means further comprising first and second mutually engagingmeans on said coupling member and said trigger member respectively thatform a pivotal connection between said coupling member and said triggermember, whereby pivoting movement of said trigger member relative tosaid handle unit causes said hollow tube to shift axially relative tosaid rod from one to the other of said first retracted position and saidsecond extended position.
 2. A surgical instrument according to claim 1wherein said means for securing said rod to said handle unit is mountedfor movement between a first rod-locking position and a secondrod-releasing position.
 3. A surgical instrument according to claim 1wherein said rod and said tool head are electrically conductive, andsaid means for securing said rod to said handle unit comprises anelectrically conductive terminal member.
 4. A surgical instrumentaccording to claim 3 wherein said terminal member extends through a holein said handle unit and comprises a first inner portion connected tosaid rod and a second outer portion projecting outside of said handleassembly.
 5. A surgical instrument according to claim 4 furthercomprising spring means urging said terminal member into said firstrod-locking position.
 6. A surgical instrument according to claim 1wherein said coupling member comprises a tube housing having a proximalend and a distal end with said proximal end of said hollow tube beingfixed to the distal end of said tube housing, and further wherein saidsecond means comprises a bifurcated end on said trigger member thatmakes a pivotal engagement with said first means on said tube housing,whereby said tube housing and said hollow tube are caused to moverelative to said rod along the axis thereof when said trigger member ismoved from one to the other of its said first and second positions.
 7. Asurgical instrument according to claim 6 wherein said handle unitcomprises first and second opposite side members secured to one another,said first and second side members defining a chamber in which said tubehousing is slidably disposed.
 8. A surgical instrument according toclaim 1 wherein said tool head is a scissors head, and said first andsecond tool members are scissors blades.
 9. A surgical instrumentaccording to claim 1 wherein said means for slidably supporting saidcoupling member is a hollow member that is mounted in said handle unitand has an elongate chamber in which said coupling member is slidablydisposed for reciprocal movement relative to said handle unit lengthwiseof the axis of said rod.
 10. A surgical instrument according to claim 1further including manually operable means for rotating said rod and saidtool head relative to said handle unit, said manually operable meanscomprising a first gear means affixed to said rod, an auxiliary triggermember pivotally mounted to said handle unit, and a second gear means onsaid auxiliary trigger member cooperatively engaged with said first gearmeans, said second gear means being adapted to cause rotation of firstgear means and thereby rotation of said rod when said auxiliary triggermeans is pivoted relative to said handle unit.
 11. A surgical instrumentaccording to claim 1 comprising a second tube that is fixed to saidhandle assembly and surrounds and conceals movement of saidfirst-mentioned tube.
 12. An instrument according to claim 11 whereinsaid second tube does not overlap said tool head but has a lengthsufficient to conceal said first-mentioned movable tube as saidfirst-mentioned tube is moved by manipulation of said trigger member.13. A surgical instrument according to claim 1 further including toolrotating means for rotating said rod and tool head relative to saidhandle assembly and said first and second tubes.
 14. A surgicalinstrument comprising:a handle assembly, said handle assembly includingfirst and second manually graspable members pivotally mounted to oneanother so that said second member is movable on its pivot between firstand second positions relative to said first member; an elongate rodhaving a proximal end and a distal end with said proximal end secured tosaid first graspable member so that said rod forms an extension of saidfirst manually graspable member; a tool head attached to said distal endof said rod, said tool head comprising first and second cooperating toolmembers movable relative to one another between first and second toolmember positions, said first and second tool members normally being insaid first tool member position; a hollow tube coaxially and slidablysurrounding said rod, said tube having a first proximal end slidablyreceived in said first manually graspable member and a second distal endthat is disposed so as to be movable into overlapping relation with saidtool head; and force transmitting means connecting said hollow tube andsaid second manually graspable member for causing said hollow tube toshift axially relative to said rod between (1) a first retractedposition when said second manually graspable member is in its said firstposition and (2) a second extended position when said second manuallygraspable member is in its said second position, said first and secondtool members being in said first tool member position and said distalend of said hollow tube being in a non-biasing position relative to saidfirst and second tool members when said hollow tube is in its firstretracted position, said distal end of said hollow tube being disposedto engage and bias said first and second tool members into said secondtool member position when said hollow tube is moved to its said secondextended position; said force transmitting means comprising a hollowhousing secured to said first proximal end of said tube and surroundingsaid rod, said hollow housing being disposed in a chamber in said firstmanually graspable member and movable in said chamber longitudinallylenthwise of the axis of said rod, and means pivotally connecting saidhollow housing and said second manually graspable member for causingsaid hollow housing and said tube to shift axially as said secondmanually graspable member is pivoted relative to said first manuallygraspable member.
 15. A surgical instrument comprising:a handleassembly, a tool head, and drive means connecting said handle assemblyand said tool head; said handle assembly comprising a handle and atrigger member pivotally mounted to said handle; said tool headcomprising first and second cooperating tool members movable between afirst open position wherein they are spaced from one another and asecond closed position wherein they are proximate to or engaged with oneanother; and said drive means comprising an elongate rod, a tubesurrounding said rod means, for releasably securing one end of said rodto said handle assembly, means for securing said tool head to theopposite end of said rod, support means attached to said handle forslidably supporting said tube for sliding axial movement relative tosaid rod, said support means comprising (1) a first housing releasablysecured to said handle assembly and defining an elongate chamber, and(2) a second housing slidably mounted in said elongate chamber, saidtube being secured to and movable with said second housing relative tosaid first housing lengthwise of the axis of said tube, and said rodextending through said second housing, and means connecting said supportmeans and said trigger member whereby manipulation of said triggermember will cause said second housing and said tube to move axiallyrelative to said rod between a first position wherein one end of saidtube is retracted from said tool head and said first and second toolmembers are in said first open position and a second position whereinsaid tube overlaps said tool head and forces said first and second toolmembers into said second closed position; said tool head and said drivemeans forming a discrete subassembly that is removably secured to saidhandle assembly.
 16. A surgical instrument according to claim 15 whereinsaid rod and said tool head are made of electrically conductive materialand said second housing and said tube are made of non-electricallyconductive material, further including a second tube surrounding andconcealing movement of said first-mentioned tube, said second tube beingsecured to said first housing and being sized so as to permit relativeaxial movement of said first-mentioned tube.
 17. A surgical instrumentaccording to claim 15 wherein said handle comprises a hollow bodyportion and said first housing extends within said hollow body portionof said handle.
 18. A surgical instrument comprising:a handle assembly,said handle assembly having at least a first handle member and a triggermember pivotally mounted to said first handle member, said triggermember being movable on its pivot between first and second positions; anelongate rod; means for securing said rod to said handle assembly sothat said rod forms an extension thereof; a tool head attached to saidrod, said tool head comprising first and second cooperating tool membersmovable relative to one another between a first open position and asecond closed position, said first and second tool members normallybeing in said first open position; a hollow tube coaxially and slidablysurrounding said rod, said tube having a first proximal end slidablyreceived in said handle assembly and a second distal end that extends tosaid tool head and is movable axially into and out of overlappingrelation with said first and second operating tool members; and forcetransmitting means connecting said hollow tube and said trigger memberfor causing said hollow tube to shift axially relative to said rodbetween (1) a first retracted position when said trigger member is inits said first position and (2) a second extended position when saidtrigger member is in its said second position, said first and secondtool members being in said first open position and said distal end ofsaid hollow tube being in a non-biasing position relative to said toolhead when said hollow tube is in its first retracted position, saiddistal end of said hollow tube being disposed to move said first andsecond tool members into said second closed position when said hollowtube is moved to its said second extended position; said means forsecuring said rod to said handle assembly comprising a conductiveterminal member having a key-shaped aperture characterized by a firstrelatively small diameter portion and a second relatively large diameterportion communicating with said first relatively small diameter portion,and the proximal end of said rod having (a) a relatively large diameterhead section sized to fit in said relatively large diameter portion ofsaid aperture but oversized with respect to said relatively smalldiameter portion of said aperture, and (b) a circumferential groovehaving a diameter smaller than said relatively small diameter portion ofsaid aperture, said terminal member and said rod being positioned insaid handle assembly so that said groove is positioned in alignment withsaid small diameter portion of said aperture, whereby said head sectionof said rod is captivated against axial movement relative to said handleassembly.
 19. A surgical instrument comprising:a handle assembly, saidhandle assembly having at least a first handle member and a triggermember pivotally mounted to said first handle member, said triggermember being movable on its pivot between first and second positions; anelongate rod; means for securing said rod to said handle assembly sothat said rod forms an extension thereof; a tool head attached to saidrod, said tool head comprising first and second cooperating tool membersmovable relative to one another between a first open position and asecond closed position, said first and second tool members normallybeing in said first open position; a hollow tube coaxially and slidablysurrounding said rod, said tube having a first proximal end slidablyreceived in said handle assembly and a second distal end that extends tosaid tool head and is movable axially into and out of overlappingrelation with said first and second operating tool members; and forcetransmitting means connecting said hollow tube and said trigger memberfor causing said hollow tube to shift axially relative to said rodbetween (1) a first retracted position when said trigger member is inits said first position and (2) a second extended position when saidtrigger member is in its said second position, said first and secondtool members being in said first open position and said distal end ofsaid hollow tube being in a non-biasing position relative to said toolhead when said hollow tube is in its first retracted position, saiddistal end of said hollow tube being disposed to move said first andsecond tool members into said second closed position when said hollowtube is moved to its said second extended position; said tool head beingremovably attached to said rod by a tongue and groove connection.
 20. Asurgical instrument according to claim 19 wherein said tongue and grooveconnection is surrounded by said hollow tube when said hollow tube is inits first retracted position.
 21. A surgical instrument comprising ahandle assembly, a tool head, drive means connecting said handleassembly and said tool head, and tool head rotation means for rotatingsaid tool head relative to said handle assembly;said handle assemblycomprising a handle and a trigger member pivotally mounted to saidhandle; said tool head comprising first and second cooperating toolmembers movable between a first open position wherein they are spacedfrom one another and a s second closed position wherein they areproximate to or engaged with one another; said drive means comprising anelongate rod, a hollow tube surrounding said rod, means for releasablysecuring one end of said rod to said handle assembly, means for securingsaid tool head to the opposite end of said rod, housing means forslidably supporting said tube for sliding axial movement relative tosaid rod, and means connecting said housing means and said triggermember whereby manipulation of said trigger member will cause said tubeto move axially relative to said rod between a first position whereinsaid tube is retracted from said tool head and said first and secondtool members are in said first open position and a second positionwherein said tube is engaged with said first and second tool members andholds them in said second closed position; said tool head and said drivemeans forming a discrete subassembly that is removably secured to saidhandle assembly; and said tool head rotating means comprising a secondtrigger member pivotally attached to said handle assembly, and meanscoupling said rod and second trigger member for causing rotation of saidrod and tool head when said second trigger member is moved about itspivot.
 22. A surgical instrument comprising a handle and triggerassembly and an operating tool assembly separably connected to saidhandle and trigger assembly;said handle and trigger assembly comprisinga handle housing having a chamber therein and a trigger member pivotallymounted to said handle housing; said operating tool assembly comprisingat one end thereof a tool head with tissue-engaging members and at theopposite end thereof a tubular housing that extends into said chamberand is releasably connected to said handle housing, said tissue-engagingmembers being movable relative to one another between a first openposition and a second closed position, said operating tool assemblyfurther including a mechanism for moving said tissue-engaging memberstoward and away from one another, said mechanism including movable meansin said tubular housing engaged and movable by said trigger member forcausing said mechanism to move said tissue-engaging members toward andaway from one another in response to pivotal movement of said triggermember; said handle and trigger assembly further comprising lockingmeans engaged with said operating tool assembly for releasably lockingsaid tubular housing to said handle housing, said operating toolassembly further comprising a rod having a proximal end and a distal endwith said proximal end extending through said tubular housing and saiddistal end connected to and supporting said tool head, a hollow housingslidably surrounding said rod, said hollow housing being slidablydisposed within said tubular housing, a hollow shaft disposed in coaxialand telescoping relation with said rod, said shaft having a proximal endaffixed to said hollow housing and a distal end that is adapted toembrace said tissue-engaging members and force them into said closedposition when said shaft is moved axially in a direction away from theproximal end of said rod toward the distal end of said rod, meanslocking said rod to said tubular housing, and means on said hollowhousing for making a pivotal connection with said trigger member,whereby pivotal movement of said trigger member relative to said handlehousing will cause said hollow housing and said shaft to shift axiallyaccording to the direction of pivotal movement of said trigger member;said operating tool assembly further including a helical gear affixed tosaid rod; and said handle and trigger assembly further including anauxiliary trigger means pivotally mounted to said handle housing havinggear teeth engaged with said helical gear so that pivotal movement ofsaid auxiliary trigger means will cause rotation of said rod and saidtool head.
 23. A surgical instrument according to claim 22 wherein saidtool head is a scissors head and said first and second tissue-engagingmembers comprise scissors blades attached to spring arms that are shapedto bias said blades to open position.
 24. A surgical instrumentcomprising:a handle unit having means defining an elongate chamber openat one end of said unit; a trigger member pivotally mounted to saidhandle unit, said trigger member being movable on its pivot betweenfirst and second positions; a hollow housing disposed in said elongatechamber and secured to said handle unit, said first hollow housinghaving a proximal end and a distal end, with said distal end thereofhaving an opening; a hollow tube having a proximal end and a distal end,said proximal end of said hollow tube extending slidably through saidopening in said first hollow housing; a slide member slidably positionedin said elongate chamber, said slide member having a proximal end and adistal end; said proximal end of said hollow tube being attached to saidslide member so as to project from said distal end thereof; an elongaterod having a proximal end and a distal end, said rod being disposed insaid hollow tube and extending through said slide member, and saidhollow tube being slidable axially relative to said rod; means forlocking said rod against axial movement relative to said handle unit sothat said rod forms an extension of said handle unit; a tool headattached to said distal end of said rod, said tool head comprising firstand second cooperating spring biased tool members movable relative toone another between a first open position and a second closed position,said first and second tool members being spring biased to favor saidfirst open position; said hollow tube having a length such that itsdistal end is movable into and out of overlapping relation with saidfirst and second operating tool members as said hollow tube isreciprocated axially relative to said rod; and force transmitting meansconnecting said slide member and said trigger member for causing saidslide member and said hollow tube to shift axially relative to said rodbetween (1) a first retracted position when said trigger member is inits said first position and (2) a second extended position when saidtrigger member is in its said second position, said first and secondtool members being in said first open position and said distal end ofsaid hollow tube being in a non-biasing position relative to said toolhead when said hollow tube is in its first retracted position, and saiddistal end of said hollow tube overlapping and biasing said said firstand second tool members into said second closed position when saidhollow tube is moved to its said second extended position.
 25. Aninstrument according to claim 24 wherein said elongate chamber has anend wall at its proximal end, and further wherein said rod is locked tosaid end wall.
 26. An instrument according to claim 24 wherein saidhollow housing is releasably secured to said handle unit.
 27. Aninstrument according to claim 26 wherein said hollow housing isreleasably secured to said handle unit by virtue of being interlockedwith said rod adjacent the proximal end of said rod.
 28. An instrumentaccording to claim 27 wherein said hollow housing has an end wall at itsproximal end and said end wall has a slot therein, and further whereinsaid rod extends through said slot and has a peripheral groove that isinterlocked with said end wall.
 29. An instrument according to claim 24wherein said hollow housing has an end wall at its proximal end and theproximal end of said rod projects through said end wall, and furtherwherein said means for locking said rod against axial movement relativeto said handle unit comprises a locking member that is mounted in apassageway in said handle unit so as to be movable between a firstrod-locking position and a second rod-releasing position, said lockingmember having a first portion that is accessible on the exterior side ofsaid handle unit and a second portion located within said handle unitthat is adapted to interlock with said rod in said first rod-lockingposition and release said rod in said second rod-releasing position, anda spring means mounted within said handle unit that urges said lockingmember to remain in said first position.
 30. An instrument according toclaim 29 wherein said second portion of said locking member has akeyhole through which said rod extends, said keyhole having a firstsection that is oversized with respect to said rod and a second sectionthat is sized and shaped to interlock with said rod, said spring meansbeing adapted to urge said locking member in a direction to cause saidsecond section to engage said rod.
 31. An instrument according to claim29 wherein said locking member is made of an electrically conductivematerial and said first portion is shaped to function as an electricalterminal post.
 32. An instrument according to claim 24 wherein saidhandle unit and said trigger member form a first subassembly, saidsecond housing and said tube comprise a second subassembly that isreleasably connected to said first subassembly and separable as a unitfrom said first subassembly.
 33. An instrument according to claim 24wherein said handle unit comprises a handle portion and a body portionintegral with one end of said handle portion, said elongate chamberbeing formed in said body portion and said open end of said chamberbeing remote from said handle portion, and said trigger member beingpivotally mounted to said body portion and extending into said chamber.34. An instrument according to claim 24 wherein said hollow housing hasan axially-extending slot confronting said trigger member, and saidtrigger member has means forming part of said force transmitting meansthat extends into and is slidable along said slot and makes a pivotalconnection with said slide member.
 35. An instrument according to claim24 wherein said hollow housing has a slot confronting said triggermember and said slide member has a lug portion, and further wherein saidtrigger member has a finger portion that extends into and is slidablealong said slot and is pivotally engaged with said lug portion, wherebypivoting movement of said trigger member relative to said handle unitcauses said hollow tube to shift axially relative to said rod.
 36. Aninstrument according to claim 24 wherein said tool head is a scissorshead, with said first and second tool members comprising scissors bladesattached to spring arms that are secured to said rod and are shaped soas to bias said scissors blades into said first open position, saidscissors blades extending across each other when in said first openposition.
 37. An instrument according to claim 24 wherein said tool headis releasably connected to said distal end of said rod by atongue-and-groove connection.
 38. An instrument according to claim 24wherein said slide member has an elongate gear-receiving chamber and aslot communicating with said chamber, and further including a helicalgear on said rod within said gear-receiving chamber, and manuallyoperated gear means movably mounted to said handle unit and engaged withsaid helical gear for rotating said rod on its axis whereby to changethe relative angular orientation of said tool head relative to saidhandle unit.
 39. An instrument according to claim 24 further includingspring means in said hollow housing in engagement with said slide memberfor urging said slide member to move said hollow tube out of overlappingrelation with said tool members.
 40. A surgical instrument comprising:ahandle assembly having first and second handle members movably connectedfor movement relative to one another; an elongate rod having a distalend and a proximal end, said rod being releasably secured at itsproximal end to said first handle member so as to form a fixed extensionthereof; a tool head coupled to the distal end of said rod, said toolhead having first and second members movable toward and away from oneanother; a hollow shaft coaxially and slidably surrounding said rod,said hollow shaft having a first end slidably received in said firsthandle member and a second end in position to be moved into and out ofoverlapping relation with said first and second members of said toolhead; drive means connecting said hollow shaft and said second handlemember for causing said hollow shaft to shift axially relative to saidrod between (1) a first retracted position when said second handlemember is moved to a first position relative to said first handle memberand (2) a second extended position when said second handle member ismoved to a second position relative to said first handle member, saidfirst and second tool head members being in a first open positionrelative to one another when said second handle member is in its saidsecond position and being forced by said hollow shaft to close relativeto one another when said second handle member is moved to its said firstposition, said drive means including a drive member that is attached tosaid first end of said hollow shaft and is slidably disposed in achamber in said first handle member, and means coupling said secondhandle member to said drive member for causing said hollow shaft toshift axially relative to said rod in response to movement of saidsecond handle member relative to said first handle member; and manuallyoperable means carried by said first handle member for rotating said rodrelative to said first handle member, said hollow shaft and said toolhead, said manually operable means being operable independently ofmovement of said second handle member relative to said first handlemember; said rod, said tool head and said hollow shaft comprising partof a discrete subassembly that is detachable as a unit from said handleassembly.
 41. An instrument according to claim 40 wherein said rod isreleasably secured to said first handle member by means comprising anelectrically conductive terminal member mounted in said first handlemember and interlocked with said rod so as to prevent removal of saidrod from said first handle member, and further wherein said hollow shaftis made of an electrically insulating material and said rod and saidtool head are made of electrically conductive material, so that saidtool head may be used for cauterization purposes when said terminalmember is connected to a source of electrical potential and said hollowshaft insulates said rod from direct contact with a patient engaged bysaid tool head.
 42. An instrument according to claim 40 furtherincluding spring means mounted within said first handle member forurging said hollow shaft into said first retracted position whereby toallow said tool head to assume its open position.
 43. A surgicalinstrument comprising:a handle assembly having first and second handlemembers movably connected for movement relative to one another; anelongate rod having a distal end and a proximal end, said rod beingreleasably secured at its proximal end to said first handle member so asto form a fixed extension thereof; a tool head coupled to the distal endof said rod, said tool head having first and second members movabletoward and away from one another; a hollow shaft coaxially and slidablysurrounding said rod, said hollow shaft having a first end slidablyreceived in said first handle member and a second end in position to bemoved into and out of overlapping relation with said first and secondmembers of said tool head; drive means connecting said hollow shaft andsaid second handle member for causing said hollow shaft to shift axiallyrelative to said rod between (1) a first retracted position when saidsecond handle member is moved to a first position relative to said firsthandle member and (2) a second extended position when said second handlemember is moved to a second position relative to said first handlemember, said first and second tool head members being in a first openposition relative to one another when said second handle member is inits said second position and being forced by said hollow shaft to closerelative to one another when said second handle member is moved to itssaid first position; and manually operable means carried by said firsthandle member for rotating said rod relative to said first handlemember, said hollow shaft and said tool head, said manually operablemeans being operable independently of movement of said second handlemember relative to said first handle member; said means for rotatingsaid rod comprising a movable trigger member mounted to said firsthandle member, a plurality of gear teeth carried by and movable withsaid trigger member, and a helical gear coaxially mounted on said rod,said helical gear being engaged by said gear teeth so that movement ofsaid trigger member relative to said first handle member will causerotation of said rod relative to said first handle member.